Circuit breaker



Feb. 2, 1932. F. w. LYLE 1,843,615

CIRCUIT BREAKER Filed Sept. 19, 1928 Hy. z.

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[ATTORNEY Patented Feb. 2, 1932 UNITED STATES PATENT OFFICE I FREDERICK w. LYLE OF SWISSVALE, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE ELECTRIC & IANUFAGTUBING COMPANY, A CORPORATION OF PENNSYLVANIA CIRCUIT BREAKER Application filed September 19, 1928. Serial No. 306,823.

My invention relates to circuit breakers and particularly to circuit breakers for controlling relatively large current values such as the oil-immersed type usually provided with arcing contacts.

An object of my invention is to provide a circuit breaker wherein burning of contacts by the arcs incident to separation thereof is reduced by providing a plurality of sets of arcing contacts for each main contact and by causing the current to be equally distributed through the sets of contacts whereby the arcs incident to separation thereof are drawn simultaneously between the contacts of each set, thus materially reducing the current through each set of contacts.

A further object of my invention is to provide a circuit breaker having the above noted characteristics wherein the circuit through each set of arcing contacts is balanced by means of a magnetic core or loop so disposed that its reactive forces balance the current through the sets of contacts and thus cause an arc to be drawn between the contacts of each set when the arcing contacts are separated.

A further object of my invention is to provide a circuit breaker having a simple and inexpensive means for balancing the current through a plurality of sets of parallel-connected arcing contacts.

These and other objects that will be made apparent throughout the further description of my invention are attained by means of the circuit breaker apparatus hereinafter described and illustrated in the accompanying drawings, wherein Fig. 1 is a front elevational View of the arcing contacts and main contacts of a circuit breaker embodying features of my invention.

Fig. 2 is a side elevational view of the apparatus shown in Fig. 1.

Fig. 3 is a front elevational view of a modified form of a current-balancing device for the arcing contacts shownin Fig. 1 and Fig. 4 is a side elevational view of the apparatus shown in Fig. 3.

Referring to the drawings, I have shown one of the main stationary contacts 5 of a heavy-duty circuit breaker having a movable contact 6, of the laminated-copper type, that is carried by a movable operating shaft 7. The main contact 5 is provided with a pair of stationary auxiliary arcing contacts 8 and 9 that constitute integral parts of it and through which current is adapted to flow, in parallel paths, to yielding arcing contacts 11 and 12. that respectively engage the arcing contacts 8 and 9 prior to engagement of the movable contact 6 with the stationary contact 5 of the circuit breaker. The movable arcing contacts 11 and 12 are yieldingly supported on the movable contact 6 by means of bolts 13 which are slidable on the contact 6, the contacts 11 and 12 being normally retained in their outermost positions by means of helical springs 14 that are disposed between them and the bracket 15 which serves to support them.

As indicated in Fig. 2, the contacts 11 and 12remain in engagement with the auxiliary arcing contacts 8 and 9 until after the main movable con-tact 6 is separated from the main contact 5. Current, therefore, continues to flow through the parallel-connected sets of arcing contacts until the movable contact 6 has been moved a predetermined distance after separation of the main contacts. Ordinarily, regardless of the precision employed in the manufacture of the arcing contacts, the arc, instead of beingv drawn between the contacts of each set, will almost invariably be drawn between the contacts of one set, due to the fact that the resistance in each set of contacts cannot be made and maintained equal.

It has been found that, where the current through the sets of contacts is balanced to equalize the current flow, arcs will be drawn between the contacts of both sets, thus reducing the current carried by each set of contacts and correspondingly reducing the burning action of the are which is correspondingly cooler and more readily extinguished. In or der to balance the current through the sets of arcing contacts, I have provided a magnetic loop 16 of figure 8 shape, made of iron and disposed to encircle the contacts 8 and 9 as indicated in Figs. 1 and 2. The flux paths around the contacts 8 and 9 are in opposite directions and, in the event of equal division '1 of the current between the two sets of contacts, equal and opposite ma netic eflects on the iron circuit are produce and the reactance of the parallel paths to the contacts is zero. Unequal current division between the sets of contacts however, sets up a reaction tending to balance the current and cause equal current division. Because of the equal division of the current between the auxiliary or arcing contacts, arcs will simultaneously be drawn between the contacts of each set.

In Figs. 3 and 4, I have shown arcing contacts and main contacts similar to those shown in Figs. 1 and 2 but the current through each set of arcing contacts is balanced by means of a magnet that is disposed between the arcing contacts 8 and 9. Since the current paths through the contacts-8 and 9 are on opposite sides of the coil, opposing flux paths are set up, the reactive force is zero and the current through the contacts is equally divided. However, when the current flow is unbalanced, reactive forces are set up in the magnetic coil or loop 17 which tend to balance the currents and equally distribute them between the contacts 8 and 9.

It will be understood that other arrangements ofthe magnetic loops may be used with out departing from the spirit and scope of my invention and that, while I have shown a circuit breaker having a pair of parallel-connected auxiliary arcing contacts, it will be understood that any desired number of sets of arcing contacts may be provided to reduce current density of each set to a point where destructive arcs cannot be formed. When more than two sets of arcing contacts are employed each pair should beinterlinked by magnetic circuits of the above-described types to insure equal division of current between them. By looping the two contact sets with magnetic circuits having difi'erent numbers of turns the current may be divided in a predetermined ratio inversely proportional to the respective number of such turns.

While I have illustrated only two embodiments of my invention, it will be apparent to those skilled in the art that various changes, modifications, substitutions. additions and omissions may be made in the apparatus illustrated without departing from the spirit and scope of my invention, as set forth in the appended claims. I

I claim as my invention:

1. The combination with a circuit breaker having a pair of sets of separable contacts connected in parallel, of a magnetic figure 8 loop encircling the two paths traversed by the respective currents through said sets.

2. In combination, in a circuit interrupter, a pair of sets of separable contacts, a pair of conductors each individual to one of said sets and adapted to conduct current thereto, and a magnetic circuit in the form of a figure 8 with n0n-intersecting limbs having one of FREDERICK W. LYLE. 

